Planar antenna



FIG. 1 is a perspective view of a planar antenna showing the claimed design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a right side view thereof; and,

FIG. 5 is a left side view thereof.

The broken lines illustrate environment and portions of the antenna that form no part of the claimed design. 

CLAIM The ornamental design for planar antenna, as shown and described. 